This is a competitive renewal application for grant RO1 MH 056350-o6 ?Prospective Study of Posttraumatic Stress in Police Officers?. The goal of this research is to advance understanding of risk and resilience factors for posttraumatic stress disorder. We have enrolled 400 police academy recruits assessed on a comprehensive set of biological and psychosocial characteristics during training. Recruits were reassessed during the first two years of police service on duty-related critical incident and routine work environment stressors, stressors and support outside of police service, and PTSD symptoms. We are requesting five years of support to follow our cohort through years three through seven of police service, a time of high risk for cumulative exposure and for leaving police service. The primary aims for the renewal are to determine prospectively if the following predictors explain PTSD symptoms across the first seven years of police service: (1) Psychosocial characteristics including IQ, trait dissociation, prior trauma, family history, neuroticism, worldview and trait anger assessed during academy training;(2) Biomarkers including awakening cortisol, acoustic startle, endocrine and psychophysiological responses to critical incident simulation and actigraphy assessed during academy training;(3) Exposure to life threatening critical incidents and peritraumatic responses assessed during police service;(4)Routine work stress, negative life events outside police service and social support assessed during police service;(5) Genetic polymorphisms;(6) Greater work hours and shift work during years 3 and 5 of police service and determine if this relationship is explained by wake after sleep onset and sleep duration as measured by actigraphy;and (7 ) Determine genetic and behavioral predictors of depression symptoms across the first seven years of police service We are well positioned to conduct the proposed research which will be the largest and most comprehensive prospective study of risk and resilience factors for posttraumatic stress in law enforcement. We have recruited and comprehensively assessed 400 academy recruits. We have successfully managed laboratories in New York and San Francisco. The academy recruits have generously agreed to participate in intensive testing including critical incident simulation and shock enhanced startle testing. We have retained nearly 84% and 82% of those due for one year and two year assessments, respectively. We have less than 3% missing data across all procedures and time points. Rates of critical incident exposure are high in the first year with 95.4 % reporting critical incidents, nearly half involving personal life threat. Results to date strongly support the aims for the renewal. After one year of police service the strongest predictors of PTSD symptoms are lower I.Q. and higher levels of trait dissociation assessed during academy training, greater personal life threat and peritraumatic dissociation at the time of incident exposure, and greater routine work environment stress and negative life events during the first year of service.